The present invention relates to a method and apparatus for recording servo control signals on magnetic record mediums for use in buried servo-controlled magnetic recording and playback systems.
In conventional magnetic recording systems operating on a buried servo control principle, a magnetic head is used to record servo control signals for track following purposes during write and readout operations. This is accomplished by moving a recording head along concentric or spiral tracks and recording a servo control signal having a frequency much lower than the frequencies of information signals. The magnetic head used for this purpose has a greater gap length than those used for writing and reading information signals. Because of the difference in gap width, magnetic flux lines produced by the servo control signals extend down to the bottom of the record medium while those produced by the information signals do not, allowing the latter to be recorded on an upper layer of the medium and leaving the servo control signals buried in the lower layer of the medium.
One disadvantage of the conventional method is that the recording hardware construction must be of high precision and stability sufficient to enable the recording magnetic head to move in a radial direction with a close tolerance over the surface of a spinning magnetic disc. Another disdvantage is that it takes a substantial amount of time to record the servo control signals.